In aircraft construction, composite materials, in particular carbon fiber reinforced epoxy resins (CRP material), are increasingly being used for the production of wings, vertical and horizontal tail surfaces and for fuselage cells of aircraft. As a result of the considerably reduced electrical conductivity in comparison with conventional aluminum fuselages of a fuselage cell that is produced for example with a CRP material, there is reduced protection of the onboard electrical systems within the aircraft, which are generally highly sensitive, with respect to external electromagnetic disturbances. These external electromagnetic disturbances are, for example, lightning strikes, radio waves and radar waves with a high field strength or the like. In addition, sources of electromagnetic interference may also be present within the fuselage cell of an aircraft itself, such as for example passengers' telecommunications equipment or portable data-processing systems, which often emit high-frequency and pulsed electromagnetic radiation. Therefore, all installations must be implemented in such a way that the sensitive onboard electrical and electronic systems, in particular the flight computer, the electronic control systems for the active aerodynamic areas of the aircraft, electrical emergency systems and the engine control are not impaired in their function in any way by such disturbances.
To minimize the interference of such onboard electrical systems by such electromagnetic disturbances, a large number of measures are widely taken. For example, twisted-together forward and return conductors or laying of lines in the vicinity of metal structures, such as for example on seat rails, stringers, ring frames or the like, may be used for the cabling of the onboard electrical systems of the aircraft. Furthermore, to achieve a particularly good shielding effect, metal meshes are used for enclosing the electrical lines and/or metal cable ducts in which the unshielded lines run. All the measures may be used on their own or in combination with one another. Both the shielding meshes, which are for example pulled over the lines from the outside in the form of net-like tubes, and the metal cable ducts always lead to a considerable extra weight of the overall cabling—quite apart from increased installation effort and a restriction of the laying paths available. In addition, the shielding meshes and the metal cable ducts make subsequent modification of the electrical installation more difficult. Furthermore, additional, generally weight-increasing, measures have to be taken in the cable ducts to avoid impairment of the mechanical integrity of the insulation of the lines, for example in the form of chafing through. However, the use of twisted conductor arrangements and/or laying in the vicinity of metal structures in the aircraft is often unsatisfactory with respect to the achievable degree of the electromagnetic protective effect, or means increased restriction on routing. On the other hand, direct integration of an electromagnetically fully effective protective mesh in the CRP fuselage cell of the aircraft would largely nullify the weight advantages of the composite material.
On account of the disadvantages of the known shielding measures for electrical lines set out above, they are only recommendable with reservations for use in aircraft with CRP fuselages.